

THE 



AMERICAN 



JOURNAL OF SCIENCE. 



Editor: EDWAED S. DANA. 



ASSOCIATE EDITORS 



Professors GEOEGE L. GOODALE, JOHN TEOWBEIDGE, 

 W. G. EAELOW and WM. M. DAVIS, of Cambridge, 



Professors ADDISON E. VEEEILL, HOEACE L. WELLS, 

 L. Y. PIESSON and H. E. GEEGOEY, of New Haven, 



Professor GEOEGE F. BAEKEE, of Philadelphia, 

 Professor HENEY S. WILLIAMS, of Ithaca, 

 Professor JOSEPH S. AMES, of Baltimore, 

 Mr. J. S. DILLEE, of Washington. 



FOURTH SERIES 

 YOL. XXII— [WHOLE NUMBER, CLXXIL] 



WITH 2 PLATES. 



NEW HAYEN, CONNECTICUT. 



1906 



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